Semi-closed rebreathing apparatus

ABSTRACT

A rebreathing apparatus adapted for connection to an open circuit demand type scuba device in which a rebreather system is used with compressed air supply tanks and demand regulators The rebreathing system has a lung bag for breathing into and out of connected in series with a CO2 scrubber for removing CO2 and an oxygen sensor for sensing the level of oxygen in the air of the rebreather. When the oxygen reaches a predetermined level, a solenoid actuates one or more exhaust valves for exhausting gas in the rebreather system allowing the demand regulator to draw additional air from the air supply tank. A manual over-rise is provided as is special solid state electronics for use in actuating the solenoid and warning lights or meters may be used.

fitted States Patent [151 3,695,261

Emmons 51 Oct. 3, 1972 [54] SEMI-CLOSED REBREATHING APPARATUS Primary Examiner-Richard A. Gaudet 72 Inventor: Donald R. Emmons, 11222 As- Assistan' Dunne tronaut Boulevard, c/o Central Atwmey"Duckwrm& Hobby Florida Industrial Park, Orlando, Fla. 32809 7] TR [22] Filed; O t. 12, 1970 A rebreathing apparatus adapted for connection to an 21 Appl. No.: 79,775

open circuit demand type scuba device in which a rebreather system is used with compressed air supply tanks and demand regulators The rebreathing system [52] US. Cl ..128/ 142.2, 128/ 147 has a lung bag for breathing into and out of connected [51] Int. Cl. ..A62b 7/04 in series with a C0 scrubber for removing CO and an i 1 Field Of Search oxygen sensor for sensing the level of oxygen in the air 128/1 98/105 of the rebreather. When the oxygen reaches a predetermined level, a solenoid actuates one or more [56] References Clted exhaust valves for exhausting gas in the rebreather UNITED STATES PATENTS system allowing the demand regulator to draw additlonal an from the air supply tank. A manual over-rise Fmney is pro 'vided as is special solid tate electronics for use 3,556,098 l/ 1971 Kanw1sher ..128/142 in actuating the Solenoid and warning lights Or-meters 2,818,860 l/l958 Holm et a]. ..l28/19l R may be 2,998,009 8/1961 Holm et a1. ..128/140 R 3,252,458 5/ 1966 Krasberg l 28/ 147 9 Claims, 6 Drawing Figures a 6 9,2224 5554 5 :57,? Mamie/26c I 5 /4 l /Z I 21/5/4 12 fienm/l/ jsfffa e 4/1 [ya/afar l/re feya/a/a r 11 0; l

/7 a 26 (j x 52 ewsor 2a 2; 20

('d/on T arc/mm: fl/bxi/e 5o/e/m/k/ I firm/fly 502M 7 24 e J W 5 27 22 Zanua '1 l Vern/e L P el ir a O s Ham SEMI-CLOSED BREA t BACKGROUND OF THE INVENTION The present invention relates to semi-closed scuba breathing equipment and particularly to a scuba breathing equipment having partial rebreathing and carbon dioxide scrubbing to improve the oxygen utilization in open circuit demand type breathing equipment.

In the past the most common type of scuba equipment has been of the open circuit demand type which utilized compressed air tanks along with demandv regulator valves which releases air from the tanks on demand from the breather by the inhalation of the air. The exhausted air is then exhausted into the surrounding water. This system, commonly known as the Aqua Lung or Bubble Machine, is generally satisfactory in shallow waters, but as a diver dives deeper the equipment becomes increasingly inefficient. The divers oxygen consumption is the same at any depth except for variations with the rate of exertion of the diver, but air being a compressible gas and at the increased pressure of greater depths under the water, the air is compressed into a much smaller volume increasing its density substantially. Thus, the air being inhaled at greater depths is compressed in accordance with the depth and while there is a greater density, the divers oxygen consumption is the same and a substantially larger portion of the air in the tanks is being exhaled into the surrounding water with each breath.

It is accordingly one object of the present invention to improve the efficiency of utilization of the oxygen from compressed air tanks for divers by the utilization of the rebreathing apparatus which exhausts gas only when the oxygen has been substantially utilized.

It has also been suggested in the past to provide closed circuit type scuba or oxygen rebreathers, which differ from the open circuit type scuba in that pure oxygen is compressed in the tank rather than air which oxygen is alternatively breathed, purified and rebreathed in a continuous cycle. This system which would typically have a lung bag, a CO scrubber and high pressure oxygen cylinder, has had little value to most scuba divers because of inherent dangers in the use of the equipment. This type equipment is also limited to 25 ft. depths. Other types of advanced scuba diving equipment include utilizing liquid air to increase the amount of air that can be stored in a tank. This type of system required that the air be maintained at relatively low pressure but at a super-cool temperature below 317 F, and requires equipment designed to maintain the liquid air in a liquid state as well as locating sources for filling the tanks. It has also been suggested to provide artificial gills to scuba divers to extract dissolved oxygen from the sea water for respiration, such as by the utilization of porous membranes. This device appears to be limited to shallow waters because of the pressure involved at deeper depths. Another such system would provide diving gear with an electrolysis system for breaking the water molecules down and capturing the oxygen for breathing by the diver.

Finally, one prior art rebreathing device would provide a pair of tanks having oxygen and a separate gas such as helium being mixed in the rebreathing system, and would include an lung bag, CO scrubber, and continuous control of the mixture of the gases from the pair of tanks. This type of system has proved to be very expensive, in addition to not being generally available for use by sports type scuba divers who would not have ready access to sources for refilling pure oxygen and helium tanks. It is accordingly an object of the present invention to provide a rebreathing apparatus which is both economical and adapted for use with compressed air tanks and with standard compressed air aqua-lung type scuba diving equipment.

SUMMARY OF THE INVENTION The present invention relates to a semi-closed rebreathing apparatus used in connection with standard scuba equipment with a compressed air tank adapted to be filled with air under high pressures and connected through a demand regulator or regulators to the mouth of the diver whereby inhalation of the diver will allow air to flow from the compressed air tanks, and exhalation by the diver of the exhaust air into the surrounding water. The addition of the rebreathing system of the present invention exhausts the air into a rebreathing lung bag which is connected in series with a carbon dioxide scrubber for removing carbon dioxide generated by the diver and which also includes an oxygen sensor for sensing the level of the oxygen in the rebreathing portion of the system and for actuating electronics which actuate a solenoid operated exhaust valve for exhausting air that has the oxygen reduced therein to a predetermined level. Additional air as required is fed into the system from the tank to the demand regulator by the breather inhaling.

This system has a manual over-ride and can have a warning meter or warning light, as desired, for warning the diver of the level of oxygen in his rebreathing equipment. The diver can utilize standard scuba equipment without the rebreathing system by over-riding the rebreathing system. The actuating electronics include a voltage amplifier for amplifying the voltage of the oxygen sensor which can operate a meter to determine the amount of oxygen in the system and includes a threshold detector for determining a desired voltage level for actuating a solenoid operated valve for exhausting air which has had a sufficient portion of the oxygen depleted therefrom into the surrounding water.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of this invention will be apparent from a study of the written description and the drawings in which:

FIG. 1 is a block diagram of the present invention;

FIG. 2 is a schematic diagram of one embodiment of the electronics utilized in the block diagram of FIG. 1;

FIG. 3 is a sectional view of one embodiment of a solenoid actuated exhaust valve with manual over-ride;

FIG. 4 is a sectional view of the solenoid valve of FIG. 3 in a second position;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4; and

FIG. 6 is a view taken along line 66 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, FIG. 1 is a block diagram of one embodiment of the present invention in which standard scuba diving rebreathing system is illustrated a dashed block and has a compressed air supply tank 11 connected to a first stage regulator 12 and to a second stageregulator 13 through a demand valve 14. A conventional scuba mouthpiece 15 is connected to second stage regulator. This is a standard Aqua-Lung system or self-contained underwater breathing apparatus of the open circuit demand type. A two stage regulator is illustrated in which the cylinder pressure of the air in the air supply tank 11 is reduced to the ambient pressure in two stages with the first stage reducing the pressure below the air supply tank pressure but well above the surrounding water pressure and the second stage reducing the pressure to the surrounding water pressure. It will of course be clear that a single stage regulator could be used with the present invention without departing from its scope. The demand valve 14 is a one-way demand valve opening in the direction of air flow on demand from the breather upon his inhalation of air. In a typical system 10, there would also be an exhaust valve for exhaling air out of the system into the surrounding water.

The present rebreathing system 16 is illustrated in block diagram form and is connected to the exhaust valve on the second regulator so that the exhaust air is fed directly into a rebreathing system. Thus the exhalation into the mouthpiece 15 forces the exhaledair past the oxygen sensor 17 through a one-way or directional valve 18 which could be a flap type valve or a ball and check valve or any other directional valve but which allows the air to pass to the manual over-ride valve 20 but prevents air from passing in the opposite direction. The air passes through a solenoid valve with a manual override 20 in which normal operation is by means of a solenoid which allows air to pass therethrough via tubing into a lung bag 22. When the oxygen sensor 17 senses that the oxygen content of the air has degenerated to a certain level the solenoid valve will be actuated allowing the exhaled air to pass through exhau'st directional valve 24 to exhaust the oxygen depleted air into the surrounding water. As will be described in more detail later, the valves 20 and 24 may be combined into a single unit in the present invention but may be done in other manners, as desired, and keeping in mind that the manual over-ride is a safety feature in the event of the failure of one valve or in the event the solenoid reversing valve sticks or fails to operate for some reason. Breathing bag 22 is a flexible bag for receiving the air in the rebreathing system but it should be noted that water pressure on the lung bag assists the air flow during inhalation of the breather. Thus the exhaled air is temporarily held in the lung bag until the breather inhales on the mouthpiece 15 at which time the one-way valve 18 prevents the air from proceeding back the same route it entered the lung bag and forces the air to pass through a carbon dioxide scrubber 25. Carbon dioxide scrubber absorbent is a commercially available item and is generally a granule absorbent of carbon hydroxide or similar material. The air passing through the carbon dioxide scrubber 25 removes carbon dioxide exhaled from the body of the breather. The air then passes through another one-way valve 26 which can be a flap-type valve similar to valve 18, but which allows the air from the lung bag to pass through the scrubber 25 and back into the mouthpiece 15, past the oxygen sensor 17. This prevents the exhalation of air into the mouthpiece from passing through the valve 26 into the lung bag 22 and forces it to pass through the normally open solenoid valve 20.

A power supply 27 may be one or more batteries such as nickel cadmium batteries, operates the electronic circuit 28 which in turn actuates the solenoid 20 when the oxygen sensor 17 detects that the oxygen content of the air in the rebreathing system has reached a predetermined low level. The solenoid valve allows air to be exhausted at 29 into the surrounding water upon exhalation of the breather into the mouthpiece 15. Inhalation by the breather following the exhausting of a substantial portion of the air in the rebreathing system, will operate the demand valve 14 first and second stage regulators to bring in additional fresh air from the compressed air tanks 11 which will first be breathed and then exhausted into the rebreathing system. Electronic circuit 28 can be provided with a meter and warning light or lights as desired to indicate the level of oxygen in the rebreathing system and to turn on a warning light if desired and as will be described in more detail in connection with FIG. 2.

Turning now to FIG. 2, a schematic diagram illustrates the oxygen sensor 17, power supply 27, and electronic circuitry 28 of FIG. 1. The oxygen sensor 17 is shown as a pair of resistance elements and is blocked off with a dash line. The sensor is represented as resistance 30 and will also have a negative temperature coefficient thermistor 31 which corrects the temperature variations in the sensor 30 and forms a part of the oxygen sensor. The oxygen sensor is commercially available and can be of any desired type such as that described in U. S. Pat. No. 2,913,386 patented Nov. 17, 1959 for ELECTROCHEMICAL DEVICE FOR CHEMICAL ANALYSIS by Leland C. Clark, Jr., which patent describes a device that can be used as an oxygen sensor and which is an electrolytic device for use in chemical analysis on a continuous basis.

The sensor 17 is the input for operational amplifier 32 which may be of many types but is illustrated as a Fairchild 735 operational amplifier integrated circuit and has the sensor 17 connected thereto at contact 2. The sensor resistance 30 is also connected to a variable or adjustable resistor 33 which resistor is connected between ground and a resistor 35 to voltage 36 which can be a negative 6 volts. A resistance 37 is coupled to the resistance 35 and to the positive input 3 of the amplifier 32. A resistor 40 couples the input 3 to ground. Contact 1 of the amplifier 32 is connected to a capacitor 41 and through a resistor 42 to connection 8 of the amplifier 32, to serve as input compensation for operational amplifier 32, while the amplifier contact 4 is connected to a minus 6 volts which is also connected through a resistor 43, and capacitor 44 to connection 5 for output compensation on operational amplifier 32. The output of the amplifier is contact 6 and is connected to a feedback circuit 45 which is coupled through a capacitor 46 to the contact 2 of the amplifier 32 and also through a resistor 47 and 48 to ground and through resistor 47 to the thermistor 31. The output has a voltmeter 50 connected between the output and ground and is connected through a resistance 51 to one input of a threshold detector circuit having a base amplifier 52 which may be a'Fairchild 741 amplifier integrated circuit and which is connected between a positive voltage 53 and a negative voltage 54. The second input to the amplifier 52 is from a power source having batteries 55 connected to ground 56 and providing a positive voltage 57 and a negative voltage 58 connected through an adjustable resistor 60 and resistance 61 for adjusting the voltage fed into the operational amplifier 52 at contact 62. This circuit is designed to form a threshold detector in which the input from the operational amplifier 32 must reach a threshold voltage determined by the batteries 55 adjusted with adjustable resistance 60. When that level is reached, an output signal from the amplifier 52 sill pass through a resistance 63 which is connected to a base electrode 64 of a transistor 65. Transistor 65 has collector electrode 66 and emitter electrode 67 with the emitter and collector connected across a voltage 50 that saturation of a transistor 65 will cause current to flow through the transistor which will in turn actuate a solenoid 68 which is the solenoid valve of FIG. 1.

In operation the sensor resistance 30 generates a signal which is adjusted in accordance with the thermistor 31 for temperature variation and which is amplified by the operational amplifier 32. The output of this signal is read on a voltmeter 50 which reading determines the oxygen level in the rebreathing system. The output is fed into a threshold detector amplifier 52 which is adjusted by resistance 60 to a desired threshold so that when the voltage applied to amplifier 52 from the amplifier 32 which is analagous to the oxygen reaching a predetermined low level in the rebreathing apparatus. This will in turn operate a power switching transistor 65 to operate the solenoid 68 which in turn exhausts the air being exhaled by the diver to the surrounding environment, such as water. A warning light could also be connected in parallel with solenoid 68 to provide an additional safety warning light if desired to give the diver a visual indication of the low level of the oxygen in the rebreathing apparatus.

Applicant does not intend to be limited to any particular circuitry design, but the following components have been found to provide an operational system and are listed by way of example only:

Resistors 31-100 Kilohms negative temperature coefficient thermistor 35-4.4 Kilohms 33-1 Kilohms adjustable 37-50 Kilohms -21 Kilohms 42-39 Kilohms 47-5 Kilohms 48-5 Kilohms 51-10 Kilohms 60-1 Kilohms adjustable 61-10 Kilohms 63-1 Kilohms Capacitors 41-0002 microfarad 44-0.00l microfarad 46-0001 microfarad Transistor 65-2N4236 Amplifier SZ-Fairchild 741 Amplifier SZ-Fairchild 735 Sensor resistance 3 will carry around 15 Kilohms Other circuit designs and values for the circuit are anticipated as being within the spirit and scope of the present invention.

Referring now to FIGS. 3, 4, 5 and 6, one embodiment of solenoid valve with manual over-ride 20, and valve 24 of FIG. 1 are illustrated in these figures as one combined unit in which the exhaled air from the mouthpiece passes through a tube 70 into the valving system illustrated generally as 71 having a casing 72 with an input port 73. The exhaust air in the position illustrated in FIG. 3 passes around the solenoid 68 and out an exhaust port 74 through an exhaust tube 75 where it goes into the lung bag 22 of FIG. 1. Solenoid 68 is connected by wires 76 from the electrical circuit as described in FIGS. 1 and 2 which actuates the solenoid from the position illustrated in FIG. 3 to that illustrated in FIG. 4 when the oxygen level is detected by the oxygen sensor as having reached a predetermined low level. Solenoid 68 is a pulling type which is resisted by spring 77 which holds it in a normally extended position and which solenoid is bolted to member 78 by brackets 80 which are in turn connected to casing 72. Casing 72 has a cylindrical sliding member 81 sliding therein and extending past an opening 82 in the casing and also having a pair of O-ring seals 83 and 84 between the cylinder 81 and the casing 72. Cylinder 81 has an end piece 85 capping one end and also has a check valve 86 at that end allowing air to be exhausted therethrough and out an exit 87 into the surrounding water. Directional valve 86 may be of any type such as a rubber flap valve or alternatively, could be a ball and check or similar type check valve. Cylinder 81 is designed to move back and forth in a telescoping manner into casing 72, and is connected at its other end by valve member 88 having a seal 90 which, as shown in FIG. 3, prevents air from passing into cylinder 81, and out the exhaust valve 86. A manual over-ride 91 is spring loaded by spring 92 to the cylinder 81, and rides in a slot 93 located in casing 72 so that the handle 94 can be grasped to force the cylinder 81 to telescope back and forth in casing 72 manually in the event the solenoid 68 sticks in one position or for any other desired reason. The manual over-ride 91 can be moved and locked from one position to another as shown in FIG. 6 by the arc in the slot 93 in a locking position 95.

FIG. 4 illustrates the valve member 88 in a second position with the spring 77 compressed, blocking the air from proceeding around the solenoid 68 and directing it through the telescoping cylinder 81 through the flap valve 86 and out the exhaust 87, thus exhausting most of the air in the rebreathing system prior to releasing solenoid 68 by sensor 17 (FIG. 1 sensing the oxygen of the freshly inhaled air from tank 11 (FIG. 1) and letting spring 77 push the valve element 88 into its normal position as in FIG. 3.

FIG. 5 shows a second end casing 85 having a bracket 78 for attaching the solenoid 68 to, which bracket has openings 96 therein for allowing the passage of air around the solenoid 68. This combined valve has been illustrated as being the most suitable way of performing the functions of the exhaust valve in connection with the electronics of FIG. 2 providing a manual over-ride system to replace automatic operation of the valves with manual operation.

The present invention, however, may have other variations, such as additional meter and an extra warning light or oxygen sensor and may have different types of valves as desired. Thus, the present invention is not to be construed as limited to the particular forms disclosed herein since these are to be regarded as illustrative rather than restrictive.

I claim:

1. A semi-closed rebreather apparatus comprising in combination:

A. gas supply means;

B. demand regulator means connected to said gas supply means for supplying gas on demand from said gas supply means;

C. mouthpiece connected to said demand regulator means for breathing into; and

D. rebreather system coupled to said mouthpiece through said demand regulator means for rebreathing gas from said gas supply means having: a. a breathing bag coupled to said mouthpiece for inhaling gas from and exhausting gas thereinto carbondioxide scrubber means connected between said mouthpiece and said breathing bag for removing carbondioxide from said gas passing therethrough; c. control means, including an oxygen sensor means located in said rebreather system for sensing the level of oxygen in said rebreather system; and

exhaust valve means connected to said rebreather system, and actuated by said control means upon the oxygen content in said rebreathing system reaching a predetermined level to exhaust gas from said rebreather system into the surrounding environment.

2. The apparatus according to claim 1 in which said gas supply means is a compressed air tank for holding compressed air.

3. The apparatus according to claim 1 in which said oxygen sensor includes threshold detection means for detecting when a voltage from said oxygen sensor reaches an adjustable predetermined level for activating said exhaust valve means.

4. The apparatus according to claim 3 in which said oxygen sensor means includes a meter for reading the level of oxygen in said rebreather system.

5. The apparatus according to claim 1 in which said exhaust valve means includes a directional valve allowing gas to escape into the surrounding water while preventing water from entering the rebreather system.

6. The apparatus according to claim 5 in which said exhaust valve means includes a solenoid actuated valve for directing air to said breathing bag in one position and through said directional valve in a second position.

7. The apparatus according to claim 6 in which said solenoid actuated valve has a manual over-ride for manual operation.

8. The apparatus according to claim 4 in which said oxygen sensor includes an amplifier for amplifying signal produced thereby.

9. The apparatus according to claim 8 in which said oxygen sensor includes a negative temperaturecoefiicient thermistor for controlling variations in temperaturem said sensor. 

1. A semi-closed rebreather apparatus comprising in combination: A. gas supply means; B. demand regulator means connected to said gas supply means for supplying gas on demand from said gas supply means; C. mouthpiece connected to said demand regulator means for breathing into; and D. rebreather system coupled to said mouthpiece through said demand regulator means for rebreathing gas from said gas supply means having: a. a breathing bag coupled to said mouthpiece for inhaling gas from and exhausting gas thereinto b. carbondioxide scrubber means connected between said mouthpiece and said breathing bag for removing carbondioxide from said gas passing therethrough; c. control means, including an oxygen sensor means located in said rebreather system for sensing the level of oxygen in said rebreather system; and d. exhaust valve means connected to said rebreather system, and actuated by said control means upon the oxygen content in said rebreathing system reaching a predetermined level to exhaust gas from said rebreather system into the surrounding environment.
 2. The apparatus according to claim 1 in which said gas supply means is a compressed air tank for holding compressed air.
 3. The apparatus according to claim 1 in which said oxygen sensor includes threshold detection means for detecting when a voltage from said oxygen sensor reaches an adjustable predetermined level for activating said exhaust valve means.
 4. The apparatus according to claim 3 in which said oxygen sensor means includes a meter for reading the level of oxygen in said rebreather system.
 5. The apparatus according to claim 1 in which said exhaust valve means includes a directional valve allowing gas to escape into the surrounding water while preventing water from entering the rebreather system.
 6. The apparatus according to claim 5 in which said exhaust valve means includes a solenoid actuated valve for directing air to said breathing bag in one position and through said directional valve in a second position.
 7. The apparatus according to claim 6 in which said solenoid actuated valve has a manual over-ride for manual operation.
 8. The apparatus according to claim 4 in which said oxygen sensor includes an amplifier for amplifying signal produced thereby.
 9. The apparatus according to claim 8 in which said oxygen sensor includes a negative temperature coefficient thErmistor for controlling variations in temperature in said sensor. 